Area Forecast Discussion
Issued by NWS Upton, NY

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363 FXUS61 KOKX 100530 AFDOKX Area Forecast Discussion National Weather Service New York NY 1230 AM EST Sun Dec 10 2017 .SYNOPSIS... Low pressure will track into the Canadian Maritimes Sunday morning. Weak high pressure will then build across from Sunday into Monday. Low pressure moving across the Great Lakes Monday night and passing north on Tuesday will weaken, while a second low develops nearby and intensifies while moving into the Canadian Maritimes through Thursday. Another low may impact the area from late Thursday into Friday, followed by high pressure on Saturday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... The snow is tapering off from west to east, and will continue to do so through the overnight period. Light accumulations across Long Island and Connecticut can be expected. The Winter Weather Advisory has been cancelled for all but Connecticut and Suffolk County, where the back edge of the snow has yet to clear. Black ice can be expected across much of the area. Temperatures will continue to slowly fall tonight, with lows ranging from the lower/mid 20s well north/west of NYC, upper 20s most elsewhere, and lower 30s on the south fork of Long Island, a few degrees below 7 PM temps. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/... Other than possibly some lingering light snow over SE CT/Twin Forks early Sunday morning, Sunday should be dry with decreasing cloud cover. It should be brisk on Sunday with a brisk W wind with gusts of 15-30 mph, strongest over NYC/Long Island. A northern stream shortwave trough will approaches Sunday night. Will see increasing cloud cover ahead of it. Cannot rule out some flurries late Sunday night over mainly over western zones ahead of the shortwave trough, however confidence in this is not quite high enough to reflect in the forecast at this time. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... A relatively active/progressive pattern will continue this week, with one low pressure system likely impacting the area Mon night into Tue morning, and perhaps another from late Thu into Fri. Most of the precip with the first system should occur on the front end via warm advection, with all snow inland, and snow changing to rain closer to the coast. Amounts should be on the light side, with about an inch closer to the coast, and 2 or 3 inches inland. Temps Tue morning as a triple point low develops nearby Tue morning should rise to the upper 30s/lower 40s, then as this low moves into the Canadian Maritimes and intensifies, blustery and colder conditions expected for Tue night through Wed night, with lows in the teens and 20s, and lows from the mid 20s to lower 30s. Some uncertainty exists on the timing and track of one or more northern stream disturbances for late week. The 00Z ECMWF tracked a leading clipper low just off to the south, while the 12Z tracked the same low well south. Models generally agree on another more consolidated system passing through late Thu night into Friday as an amplifying long wave upper trough to the west approaches and passes through. As a result have broad- brushed low chance PoP from Thu night into Friday. Temps should be cold enough for precip with these potential systems to be mainly snow. After these systems pass, zonal flow should return, with temps returning closer to average, if not by Sat, then by early next week before the mean trough in the East reloads and colder air returns mid next week. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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Low pressure tracks into the Canadian Maritimes this morning. Snow will taper off through 8Z from west to east. Ceilings will improve to MVFR as the snow ends, then VFR by 12Z. MVFR is again possible with ceilings around 3000 ft after 15Z. VFR returns tonight. Winds back to the northwest this morning, then west during the day with gusts around 20 KT. Winds subside after 00Z Monday. .OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY... .Late tonight...VFR. West winds less than 10 kt. .Monday...VFR. Iso flurries in the morning. .Tuesday...MVFR or lower with early morning mixed pcpn, changing to rain by mid-morning. Dry aftn with CHC VFR by late. .Wednesday...VFR, chc MVFR/-shsn east of city terminals. NW gusts 30- 35 kt. .Thursday...VFR .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .Sunday night...VFR. W gusts around 20 kt. .Monday...VFR. Iso flurries in the morning. .Tuesday...MVFR or lower with early morning mixed pcpn, changing to rain by mid-morning. Dry aftn with CHC VFR by late. .Wednesday...VFR, chc MVFR/-shsn east of city terminals. NW gusts 30-35 kt. .Thursday...VFR
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&& .MARINE... SCA in effect for all waters, first on the ocean tonight as winds back NW after passage of offshore low pressure, with seas building to 5-8 ft and winds gusting up to 25 kt, then on all waters Sunday into Sunday night as winds back W and gust to 25-30 kt. These conditions should linger on the ocean into Monday as an upper level disturbance passes across. Low pressure developing nearby on Tue should strengthen on its way to the Canadian Maritimes, with SCA developing daytime Tue on the ocean waters. As the low intensifies, gales are likely on the ocean Tue night and on all waters Wed into Wed night. Gales could linger on the eastern ocean waters into Thu morning, otherwise SCA conds expected daytime Thu, with quiet conds returning Thu night as the Maritimes low loses its influence. && .HYDROLOGY... Around 0.2 to 0.5 inches of additional liquid equivalent QPF expected through tonight. With this mainly if not entirely in the form of snow, no significant hydrologic impacts expected. No hydrologic impacts are anticipated thereafter. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. See our headline news on the web at: http:/ The Riverhead NOAA Weather Radio Station WXM-80 (162.475 MHz) is currently out of service. NWS technicians are working with Verizon to restore service. An estimated time of return to service is not currently known. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Winter Weather Advisory until 4 AM EST early this morning for CTZ005-006-009. Winter Weather Advisory until 6 AM EST early this morning for CTZ007-008-010>012. NY...Winter Weather Advisory until 6 AM EST early this morning for NYZ078>081. NJ...None. MARINE...Small Craft Advisory from 6 AM this morning to 6 PM EST this evening for ANZ335-338-345. Small Craft Advisory from 6 AM this morning to 6 AM EST Monday for ANZ330-340. Small Craft Advisory until 6 PM EST Monday for ANZ350-353-355.
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